An air-conditioning system in a motor vehicle typically cools the passenger compartment of the vehicle and also heats it. In motor vehicles driven by an internal combustion engine, the waste heat of the exhaust gas can be used to heat the passenger compartment of the motor vehicle. To cool the compartment, an air-conditioning compressor is mechanically driven by the internal combustion engine in order to generate cold air and uses part of the kinetic energy of the internal combustion engine for air-conditioning.
This means that a portion of the fuel consumed by internal combustion engines is used to operate the air-conditioning system. However, in the case of vehicles with low-power internal combustion engines and/or in the case of vehicles with a hybrid drive (e.g., internal combustion engine and electric motor) or else in the case of electric vehicles, the expenditure of energy for temperature control becomes more and more significant in light of the overall energy efficiency.